Two-stroke multicylinder engine



May 2, 195 0 M. ECHARD TWO-STROKE MULTICYLINDER ENGINE Filed July 10,1945 2 Sheets-Sheet l j /wca ELY/MED.

xiv/Q0 #64 2 Sheets-Sheet 2 I Filed July 10, 1945 Q Maeta fax/0E0.

I ting is carried out with maximum Patented May 2, 1950 'UNITED STATESPATENT orrics TWO-STROKE MULTICYLINDER ENGINE Marcel Echard,Neuilly-sur-Seine, France Application July 10,1945, Serial No. 604,111

"In France July 3, 1944 Section 1, Public Law 690, August a, 1946 Patentexpires July 3, 1964 planes; this however does not exclude thepossibilitie's of all other applications for which it is suitable. r

The essential qualities looked for in an airplane engine are: a lowspecific weight, an extreme simplicity and reliability combined with thepossibility of a good streamlined cowl; in addition, a highly uniformtorque and moving parts 'with an excellent balance are desired and sois-ga reduction of the fuel consumption to a minimum. Generally inaircraft engines such advantageous properties are obtained to a more orless greatextent at the expense of mechanical comp1ications involvingdifllcult and costly "machining methods.

In the engine according to this invention the desired qualities areobtained by new arrangements'and combinations of some of the parts andmeans with a view to developing a multicylinder engine type whichoperates on the two-stroke cycle principla' This cycle gives a highpower-weight ratio and makes it possible to dispense with a great manydelicate parts liable to get out of order, wear or break. In particular,in the four-stroke engine,

the provision of valves sets a limitation on one' two-stroke cycle, thisengine, which belongs to the so-called radial type, operates on theuniform principle by means of twin cylinders controlling the intake andthe exhaust respectively, one head being common to both of the saidparallel cylinders according to a known principle.

.This arrangement, in combination with theangular displacement through a,small extent of the crank pin in each group of intake and exhaustcylinders respectively allows obtaining a phase difference between thescavenging of the burnt gases and the filling with new gases at thedesired relative pressure which depends on the operation of the loadingand scavenging air-compressor to be dealt with hereafter.Carburetefliciency by means of a pump.

The air-compressor is arranged co-axially with the main driving shaft infront of that cylinder z group, which controls the intake and is nearestth propeller.

Since the compressor is rotated in the same direction as the drivingshaft through the medium of a gearing, its speed relatively to saidshaft is very low or null depending on the ratio of the gearing.

As a matter of fact, the rotor of the compressor rotates at a speed,which depends on the gear ratio of said gearing. By a suitable selectionof the gears, it is possible to give the compressor a speed of rotationwhich is but little different from that of the shaft or even a speedequal to that of said shaft. As the compressor and the shaft rotate inthe same direction, the consequence is that their relative speed is lowor even equal to zero.-

This involves unquestionable mechanical'advantages as to the wear andlife of the'intermediate elements; the engine shaft also serves as theaxle of the compressor vanes, which allows doing away with said part andsaving as nine weight.

The burnt gases are taken away through a two-channel annular collectorwhich is so ar-' ranged that in a six-cylinder bank or row the threeeven cylinders shall discharge into the one channel and the three oddcylinders shall discharge into the other.

avoided, and a possible dephasing' of the acousti"-' cal impulsesprovides a reduction in the noiseof the exhaust. a

As a result of the described combination of the characteristics,locations andarrangements ot the various parts, the overall dimensionsand es pecially the front-section (maximum section) are decreased, andthe ordering of the various ele-" ments lengthwise of the engine allowsproviding the latter with a streamlined cowl with the least possibledrag. Said cowl possesses as correctanoutline as the designer maydesire.

At the same time the weight of the whole-"is the num'-" Overpressuresarising from interactions between the cylinders are thus;

An embodiment is shown in the appended dl'fiw f nimatlcal illustrationof" cut connectingthe com:-

fitted; 5 is the ring-shaped twin-channel ex-r haust manifold, 6 theback casing in which mag-' netos, pumps, dynamos and likeeaccessorytap-.- paratus are enclosed.

Rigidly secured on the driving shaft I as shown in Fig. 2 is the pinion8 which, meshes iwithza pinion 9 rigid with an additional pinion I ll;Pinions 9 and ID are rotatable abouta common axis; said pinion mesheswith a sunwheeljli rigid with a rotor 32 constituted by a cylindricalmember forming a rotor adapted to rotate eccene trically with referenceto. the driving shaft 1.

Names: l2 rotate-freelyround thedrivi-ng shaft 1 I as shown moreparticularly in Fig." The cylindrical rotor=3z :isiprovided-withlongitudinal slots: the. walls -of which-assume-acylindrical shape; eachslot .holding.;;rotatablytwo semi-cy- 1indrical=rods ,33. Between the flat surfacesaof the semi-cylindrical rods 33 isformed a passage fontherfreez-sliding pfethervanes I 2;. The-roto1a32drives etherblades -12 .into ..-rotation throughethe agency of r1. the;semi-cylindrical. rods 33. The spacing? between'etwo successive blades-.l 2 -may bewariables Thewrotational speed .ofTpinion-i I l and conse--quentlygthe :feedand. pressure of a-the. compressorcanwbezaltered-easiiy by;replacing and H or 8 .andwB -by1 :-two pinionshaving the.same distance between centers but a greater or less number,-ofteethrthan the replaced pinions.

. Ohrthe other hand .the'irotor. of: the compressor- 32. is -,-driven-bytheapiniont carried-by the crankshaft and by;the-pinions.-9, l0 and -I Iit rotates (Fig;;.3): in the samedirection as :saidshait and'- at thesame speed as the latter if the ratio rho-- tweenstheflgea-rswissuitably; chosen. This speed may. howeverqbe modified. and then. thespeed .of then-rotor may sbecomepositive or negative-with referencetoxthecrank'eshaft; As the :2 1'0130113. drives -the compressor bladesthrough thetzagencyof; the semi-cylindricaL rods 33:.randras said:bl-a-desiarefreely mounted on the crankshaft whicl'rserves-onlyas asupport therefor,--tlie;zdisplacement; of; the: semi-cylindrical-rodswhich hold the blades fast with reference'toathe crankshaft-islimited,llflithe casezwhere --.the rotor and dice crankshaft-rotate. at. thesame -speed to am; oscillating; -re'ciprocating;; movement.

jviewythe two :corjnp anion scylinders: i %and .16 have a commonz head;:at -the;;moment when: piston" l l v in IS beg-ins to;close-theintakeportthe-piston l-flr-a-in' .cylin'der. 16- has almost: closed. theexhaust ports. As thezintakeiport fist-being :closedsithei comptessorzcdmpletesa the :filling of. -.cylindersral 5 ands! 6inrelationmith the. iworkingz plfessure for.

which said compressor. isdesigned.

In the case of a delayed mechanical carburetting, i. e. one that takesplace following the intake of a given volume of air, the scavenging ofthe burnt gases is completed before the piston 18 has closed the exhaustport 19 which leads into the exhaust manifold 20.. Thelatter collectsthe burnt gases from half the number zof cylinders, namely, every otherone.

The dephasing in the closure of the ports in cylinders l5 and I6 isbrought about by the angularydisplacement of the related crank pins 2!and 22, crank pin 2| for instance being at its lower dead centre whilecrank pin 22 is already beyondthe same inthe direction of rotation.

Aby-pass arrangement allows providing for a direct. return between thedelivery and the suctioncndsof the compressor so as to reduceautomatically the output of said compressor into the engine when thelatter is idling.

Visible at 23 (Fig. 3) is a region, in the delivery manifold of thecompressor, which can be. -set into communication throughtheby-passvalve 24--with+the space in which suctiomtakes place.

Saidvalve-is actuated by a lever. 23 connected with a flap valve 21 (orpossibly a carburetor throttle valve) by lever ZE-and link 29n Thisgearas a whole. is actuatedin turn by the control rod- 39.- connectedwith'thelhand-lever operated by the pilot or the manln chargeoftheengine.-...

It .isalways possible where necessary vtov in-v corporate an altimetricvcorrecting device to, the

system at any desired point. thereof.

The leverage .29-30 .is. designed and '28-may provide .for the openingof .the bye pass valve zdsimultaneously with the closingpf.

the flap or throttle valve 2'! inserted in the.suc-.. tion. pipe, of..the :compressor and reversely.

The compressor may. .be .fed. by ;a carburetor. in. which. case-.thefiapvalve .21 is constituted by. a carburetor .throttle valveof,the.type.generally used in such cases,

When the flap valve 2'! is closedpartly, the.

suction, end of. the compressor while the engine. cylinders are fed to agradually reduced extent. 1

Thetype of. engine which. is the subject-matter of. this. inventionlends itself most advantageous- 1y .to the provision of a mechanicalcarburettin'g by means, of fuel pumps, whether thefuel be fed at highpressure directly into the" head or be injected at low pressure.

' In the latterevent the low-pressure injector, anclatomizer. 3 islocated between two intakeportsfor the purpose of conferringhomogeneousness' to the mixture; Besides, no counterpressure is exertedat that point upon the *in-' je'cto r by the compression orexplosion'pressures developed in thecyliridrs since in theascendingstrok'e of" piston I! the latter covers the-iri- J'ector 31' at the sametirne as the-intake portsand uncovers'sit 1m its" descending stroke:onlyli: after the exhausttiis openeds" This; arrangementsis:azimostaimportantfone since it; makes it possi'a ble ato a do; away:-inthe; x-inj ectorv and atomizer 1 with cut-off needle or like valveswhich 1 are very a easilyvdamageableby reason oftheir-small-size and'ofthehighspeedsattained thereby in highly rated engines. Z It is onlynecessary accurately to .1ensuresthat: the esarne-shall .take

place: into: the, cylinders; subsequent. the.

im. a manner. such thattherelative positioning-0fthe leversIE to timetheefuelt injection.

scavenging by pure air which thoroughly drives out the waste gases whileproviding for an efficient cooling from the inside. On the other hand,the exhaust, when the fuel is being injected, must be sufficiently cutoff, as a. result of the dephasing, to ensure that even the smallestamount of fuel can not get into the exhaust manifold without havingdeveloped useful power.

The injection of fuel into the cylinder is performed at the end of theperiod of admission of air into th cylinder. The amount of air admittedinto each cylinder may be superabundant, in other words the volume ofair admitted may be higher than the cylinder charge; the excess amountof gases is exhausted and thus cooperates in the cooling of the insideof the cylinder.

The exhaust opening is partly closed when the injection begins and isentirely closed at the end of the injection stroke.

What I claim as my invention and desire to secure by Letters Patent is:

In an internal combustion aircraft engine having uniflow pairedcylinders, a crank shaft for the cylinders and a drive shaft connectedto and extending outwardly from the crank shaft, the improvement whichcomprises a volumetric compressor having a housing, a manifoldcommunicating with the discharge of said compressor positioned withinsaid housing and having ports communicating with the cylinders, saidcompressor housing being mounted to surround the drive shaft andextending substantially co-axially therewith, said compressor havingrotatable vanes, said vanes being journalled directly on said driveshaft, a rotor surrounding said drive shaft and mounted eccentricallythereof to rotate said vanes on said drive shaft, and gearing betweensaid drive shaft and said rotor to rotate said rotor at substantiallythe same speed and inthe same direction as said drive shaft, saidcompressor functioning as the supercharger for the uniflow pairedcylinders of the internal combustion aircraft engine.

MARCEL ECHARD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,012,440 Reichhelm Dec. 19, 19111,350,159 Johnson Aug. 1'7, 1920 1,607,383 A-urand Nov. 16, 19261,811,625 Greening et al. June 23, 1931 1,815,868 Schenk July 21, 19311,882,448 Roche Oct. 11 1932 1,963,423 Shoemaker June 19, 1934 1,999,374Pavlecka Apr. 30, 1935 2,133,578 Schjolin Oct. 18, 1938 2,159,209 HazenMay 23, 1939 2,283,694 Perrine May 19, 1942 2,311,936 Elfes et a1. Feb.23, 1943 FOREIGN PATENTS Number Country Date 375,668 Great Britain June30, 1932 83,945 Sweden July 23, 1935

